The present invention refers to an arrangement for sealing the end rolling bearings of a support roller in belt conveyors.
As it is known in the art, the life of the rolling bearings of a belt conveyor roller, even if said rolling bearings are correctly dimensioned to the load conditions to which they will be submitted, can be seriously affected by contamination, if the seal does not give an adequate protection against the entrance of dust and humidity. With the aim of increasing to a maximum degree the useful life of such rolling bearings, many complex sealing systems have been developed. In a general way, it can be said that the improvements which were introduced in the known seals resulted in a physical increase of the seal itself.
As illustrated in FIGS. 1 and 2, in the prior art sealing systems, the seal is disposed around the roller shaft, between an end of the latter and the adjacent rolling bearing. In these known conventional solutions, the physical increase of the seal results from its constructive sophistication, although minimizing the contamination of the rolling bearing by the undesirable entrance of dust and humidity, it increases the distance "D" between the rolling bearing and the respective end of the roller shaft. Thus, the rolling bearing is further spaced away from the shaft support point in the conveyor support, increasing the bending moment which is transmitted to the shaft and causing angular deflections in the latter, all of which are detrimental to the useful life of the rolling bearing.
Therefore, in the prior art constructions, the sophisticated and bulky seals need large and stiff shafts for the roller, thereby further requiring rolling bearings which are overdimensioned in relation to the load applied thereon. The use of thinner shafts dimensioned according to the rolling bearings which are chosen based on the load applied thereon, leads to substantial deflections at the end portions of the shaft, causing a significant decrease in the useful life of the rolling bearings.
Another inconvenience of said constructions which impairs the seal effectiveness with time, is the annular positioning of the elastomeric sealant. Due to the large distance which separates the sealant from the roller shaft and from its fastening point to the sealing system up to its free end, the sealant is constantly submitted to high tangential speeds at the contact region that causes friction with the relatively movable portion of the roller shaft. At the proximities of the sealant free end, such tangential speed causes friction wear which corrodes the edge of the elastomeric sealant free end, due to the presence of impurities on both contacting surfaces.
Moreover, the more the sealing system is spaced away from the roller shaft, the greater is the probability of sealing failures occurring, as the annular surface covering area to be protected increases.